I have a Colido 2.0 Plus 3D Printer.
But when I want to print an object, the printer ask me a G-Code.
Where I find this G-Code?
You must convert the objects you want to print into gcode. Slicers are the software component doing this. The host has 3 slicers included that you can use for this. Read our docs on www.repetier.com to see how this should work.
edited November 2017
The Print-rite Colido Repieter ask me the G-Code even if I want print a model which are in the SD-Cards as test!
I use the software in the SD-Card Repieter-Rite Colido Host V1.55.
Also, I think that this model is already in good format.
What Can I do?
Since I can not see what you did I can not say that this is correct or not. All I know is that printers can only print gcode and you get models as stl/obj so you need to slice them. Also in sd card it needs to be a gcode file and you can start these prints only from the sd card tab.